The Senate Judiciary Committee has asked Supreme Court nominee Brett Kavanaugh about another allegation of misconduct, according to redacted transcripts of phone conversations between committee staffers and Kavanaugh made available by the committee Wednesday evening.

The allegation was made in a letter sent to Sen. Cory Gardner, R-Co. on Sept. 22. According to the unnamed author of the letter, Kavanaugh drunkenly slammed a woman against a wall outside a bar in Washington D.C. in 1998. Kavanaugh had been out for the evening with the daughter of the woman who wrote the complaint as well as several friends.

"Her friend was dating him, and they left the bar under the influence of alcohol. They were all shocked when Brett Kavanaugh, shoved her friend up against the wall very aggressively and sexually," the letter said. The letter said at least four witnesses were present, though it did not provide any names.

Kavanaugh denied the allegation during the phone call, saying "no" when asked if the events described in the letter ever occurred.

The embattled federal appeals court judge is facing down three other accusers who allege that he sexually abused them decades ago. The allegations have thrust Kavanaugh's Senate confirmation vote, once assured, into uncertainty.

Notably, all of the allegations involve heavy drinking, though the latest is said to have occurred more than a decade later than the others. While Kavanaugh's other accusers allege misconduct from Kavanaugh's high school and early college years, by 1997, and into 1998, Kavanaugh was a partner at Kirkland & Ellis, a respected D.C. law firm. Kavanaugh was also a lawyer working on independent counsel Kenneth Starr's team investigating President Bill Clinton during a period in 1998.

He has denied all the allegations, saying that they are "smears." He will tell the Judiciary Committee Thursday that he has been subject to "grotesque and obvious character assassination," according to his prepared remarks released Wednesday.

The White House, Gardner, and an attorney for Kavanaugh did not immediately respond to a request for comment from CNBC about the latest allegation.